I really have no idea how hot it actually gets and how long it lasts. I don't think it heats up too much as I have taken the alfalfa that is breaking down that is "hot" and held it in my hand with fist closed and it's not hot enough to burn my hand so unless you are sitting your plant bare root on top of a pile of alfalfa then I would say it's not going to cause much damage if any. Here the alfalfa breaks down pretty quickly since we water daily. The last load of pine bark we got in has been hotter than any heat I have felt from the alfalfa.
I would also think that it would depend on soil temps, moisture, and other things. Alfalfa will take longer to break down in dryer soil than in soil that is watered daily or often so it may put out more heat. I believe Tommy had said somewhere (maybe when he was at our club speaking) that after he puts down alfalfa he waters it in for about 6 hours to help break it down. he might of been saying that about something else I really can't remember.
